Surface-modified post-crosslinked adsorbents and a process for making the surface modified post-crosslinked adsorbents

ABSTRACT

Disclosed is a surface-modified polymeric adsorbent material comprising a porous post-crosslinked polymer as a substrate and at least one surface-modifying polymer. The porous post-crosslinked polymer comprises a polymer of at least one monoethylenically unsaturated monomer, wherein the polymer has been post-crosslinked in a swollen state in the presence of a Friedel-Crafts catalyst. A process for preparing the surface-modified polymeric adsorbent materials, and the use of these materials in the separation of organic compounds, enantioselective synthesis and resolution of racemic mixtures are also disclosed.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of Application Ser. No.08/331,073, filed Oct. 28, 1994, now U.S. Pat. No. 5,519,064.

BACKGROUND OF THE INVENTION

This invention concerns a polymeric adsorbent material comprising apost-crosslinked polymer as a substrate which has been surface-modifiedwith at least one polymer and to a process for preparing such polymericadsorbent materials. The polymeric adsorbents have controlled poregeometry and variable chemical functionality. The polymeric adsorbentsmay have an interpenetrating polymer network.

The rapid advances in bio-technology along with consumers' desire fortastier, healthier, and more esthetically pleasing food and beverageproducts have created urgent needs for highly selective, efficient, andcost-effective processes for separating various chemicals from complexmixtures. Environmental concerns for cleaner air, water and soil havefurther increased a demand for better and improved separation systems.Thus, the demand for better separation materials is rapidly movingbeyond the realm of the conventional adsorbents and membranes.

Interpenetrating polymer networks (IPN) using polystyrene/polystyrene asmodels for ion-exchange resin matrices (IER-IPN) were first introducedin the sixties (see for example, J. R. Millar, Journal of ChemicalSociety, p. 1311 (1960); p. 1789 (1962); and p. 218 (1963)). Morerecently, IER-IPNs have been described in "Sulfonic Acid Resins WithInterpenetrating Polymer Networks", in D, Klempner and K. C. Frisch,Ed., Advances in lnterpenetrating Polymer Networks, Volume II, TechnomicPublishing Co., Inc., Lancaster, Basel, (1990), pp. 157-176.

One of the drawbacks in IPN technology has been the necessity of thefirst crosslinked polymer to adsorb, imbibe, or swell in the monomer orsecond polymer to create molecular interpenetration. Until now,molecular interpenetration was thought to occur only in the cases wheretwo or more polymer phases within the IPN possessed similar solubilitycharacteristics or solubility parameters. In the case of crosslinkedpolymer substrates, the substrate polymer is either insoluble or swellsin the presence of a compatible monomer or polymer possessing similarsolubility parameters. Depending on the free energy of mixing, thecrosslinked polymer either phase separates or fails to imbibe themonomer or second polymer (see for example, C. H. Sperling,Interpenetrating Polymer Networks and Related Materials, Plenum Press,New York, (1981)).

Another drawback to conventional IPNs prepared from conventional highlycrosslinked adsorbents is the loss in porosity as the pores of the firstpolymer are filled with the monomer or second polymer. The final poredistribution in these IPNs is determined by the amount of the secondpolymer and the mixing thermodynamics governed by the Flory Hugginstheory.

Polymeric adsorbents and ion exchange resins of macronet type polymers(post-crosslinked) are described in U.S. Pat. Nos. 4,263,407 and4,191,813. These patents teach that the macronet adsorbents obtainedfrom macroreticular (macroporous) copolymers may be used as substratesfor hybrid copolymers and ion exchange resins. In a method for preparingthe hybrid copolymers and ion exchange resins, a liquid monomer mixturecontaining a crosslinking monomer is added to an aqueous suspension ofthe macronet adsorbent, which liquid mixture is imbibed into the poresof macronet adsorbent and is polymerized therein. The resulting hybridproduct may then be converted into an ion exchange resin by appropriatefunctionalization in the conventional manner.

It is an object of this invention to provide surface-modified adsorbentmaterials which have useful surface area, desired porosity, surfacefunctionality and physical properties for a variety of chromatographicseparations.

SUMMARY OF THE INVENTION

It has been discovered that the use of porous post-crosslinked polymeras a substrate makes the micropores of the polymer gel interior surface(pores with less than 20 Angstroms (2 nm) in diameter) accessible to alarge variety of molecules due to the large amount of microporositycreated by the displacement of the polymer chains in the swollen stateduring post-crosslinking, and makes it possible to obtainsurface-modified polymeric adsorbents with minimum loss of usefulsurface area and larger pores (larger than micropores) of the substratepolymer. The use of porous post-crosslinked polymer as the substratealso makes it possible to sufficiently entangle, crosslink, or graftdifferent polymers thereon and prevent leaching of the polymers, withoutthe necessity of the two polymers having similar solubilitycharacteristics or solubility parameters. It has been further found thatwhen a surface-modifying monomer having similar solubilitycharacteristics as the polymer substrate is incorporated into thesubstrate, the loss in porosity is less than what would be expected fromsimple pore filling of the substrate.

"Post-crosslinked polymer" means alkylene bridged polymer produced bycrosslinking in a swollen state, in the presence of a Friedel-Craftscatalyst, lightly crosslinked gel or macroporous polymers of at leastone monoethylenically unsaturated monomer.

In one aspect, the present invention concerns a polymeric adsorbentmaterial comprising a porous post-crosslinked polymer as a substrate andat least one surface-modifying polymer, the porous post-crosslinkedpolymer comprising a polymer of at least one monoethylenicallyunsaturated monomer, wherein the polymer has been post-crosslinked in aswollen state in the presence of a Friedel-Crafts catalyst.

In another aspect, the present invention concerns a process forpreparing a polymeric adsorbent material comprising incorporating atleast one surface-modifying polymerizable monomer or polymer onto aporous post-crosslinked polymer substrate, and immobilizing thesurface-modifying monomer or polymer thereto, the porouspost-crosslinked polymer comprising a polymer of at least onemonoethylenically unsaturated monomer, wherein the polymer has beenpost-crosslinked in a swollen state in the presence of a Friedel-Craftscatalyst.

In still another aspect, the present invention concerns a method forseparation of organic molecules comprising contacting a mixture oforganic compounds with a surface-modified polymeric adsorbent, whereinthe surface-modified polymeric adsorbent comprises a porouspost-crosslinked polymer substrate and at least one surface-modifyingpolymer, the porous post-crosslinked polymer comprising a polymer of atleast one monoethylenically unsaturated monomer, wherein the polymer hasbeen post-crosslinked in a swollen state in the presence of aFriedel-Crafts catalyst.

In yet still another aspect, the present invention concerns a method forenantioselective synthesis of an organic compound from a syntheticprecursor comprising contacting the synthetic precursor with asurface-modified polymeric adsorbent, and reacting the syntheticprecursor with a reactant, wherein the surface-modified polymericadsorbent comprises a porous post-crosslinked polymer substrate and atleast one optically active surface-modifying polymer, the porouspost-crosslinked polymer comprising a polymer of at least onemonoethylenically unsaturated monomer, wherein the polymer has beenpost-crosslinked in a swollen state in the presence of a Friedel-Craftscatalyst.

In still another aspect, the present invention concerns a method forresolution of a racemic mixture comprising contacting the racemicmixture with a surface-modified polymeric adsorbent and separating anenantiomer thereof, wherein the surface-modified polymeric adsorbentcomprises a porous post-crosslinked polymer substrate and at least oneoptically active surface-modifying polymer, the porous post-crosslinkedpolymer comprising a polymer of at least one monoethylenicallyunsaturated monomer, wherein the polymer has been post-crosslinked in aswollen state in the presence of a Friedel-Crafts catalyst.

The polymeric adsorbent materials can be prepared from post-crosslinkedcopolymers of different shapes and forms such as beads, membranes,fibers and the like. The polymeric adsorbent materials of the inventionare useful for separation of solutes from solutions, as chromatographicpacking materials in chromatographic separation systems, as catalysts inchemical processing, as ion exchange resins when appropriatelyfunctionalized, in separation of proteins, in resolution of racemicmixtures, as asymmetric templates in enantioselective transformation andthe like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 through 6 illustrate Transmission Electron Micrographs(300,000X) of 300 Angstrom thick cross-sections of respective polymersas described below.

FIG. 1 illustrates a Transmission Electron Micrograph of porouspost-crosslinked polymer comprising a macroporous polymer of 6 percentdivinylbenzene and 94 percent styrene, which has been post-crosslinkedin the presence of a Fridel-Crafts catalyst and further aminated withdimethylamine.

FIG. 2 illustrates a Transmission Electron Micrograph of the polymericadsorbent of the invention comprising the porous post-crosslinkedpolymer of FIG. 1 as a substrate and 7 percent Nylon as thesurface-modifying polymer.

FIG. 3 illustrates a Transmission Electron Micrograph of the polymericadsorbent corresponding to FIG. 2 except with 20 percent Nylon as thesurface-modifying polymer.

FIG. 4 illustrates a Transmission Electron Micrograph of the polymericadsorbent of the invention comprising the porous post-crosslinkedpolymer of FIG. 1 as substrate and a surface-modifying polymercomprising moieties derived from 25 percent of an epoxy resincrosslinked with an amine.

FIG. 5 illustrates a Transmission Electron Micrograph of a porouspost-crosslinked polymer comprising a macroporous polymer of 6 percentdivinylbenzene and 94 percent styrene, which has been post-crosslinkedin the presence of a Fridel-Crafts catalyst and further aminated withmethylamine.

FIG. 6 illustrates a Transmission Electron Micrograph of theinterpenetrating polymer adsorbent of the invention comprising theporous post-crosslinked polymer of FIG. 5 as the substrate polymer and asurface-modifying polymer comprising moieties derived from 10 percentsilicone epoxy grafted to the aminated substrate polymer.

DETAILED DESCRIPTION OF THE INVENTION

Substrate Polymer

One of the polymers of the adsorbent of the invention is a substratepolymer. The substrate polymer is a porous post-crosslinked polymercomprising at least one monoethylenically unsaturated monomer whereinthe polymer has been post-crosslinked in a swollen state in the presenceof a Friedel-Crafts catalyst.

The term "polymer", as used herein in reference to the substratepolymer, refers to homopolymers of monoethylenically unsaturatedmonomers and copolymers of at least one monoethylenically unsaturatedmonomer and a polyunsaturated crosslinking monomer.

The porous post-crosslinked polymers are preferably produced fromlightly crosslinked gel or macroporous polymers that possess goodswelling characteristics and are described in U.S. Pat. Nos. 4,965,083;4,950,332; and 4,263,407.

The "macroporous polymer" is broadly defined to include polymersprepared by polymerization of monomers in the presence of an amount ofan inert organic diluent sufficient to cause phase separation of theresulting polymer from unreacted monomer and the diluent.

The "gel type polymer" is broadly defined to include polymers which maybe prepared by polymerization of the respective monomers in the presenceof an amount of an inert organic diluent without phase separation of theresulting polymer from unreacted monomer and the diluent.

The macroporous polymers are prepared by the methods described in GermanPatent No. 249,274 A1 and U.S. Pat. Nos. 4,965,083 and 4,950,332.

The gel polymers are prepared by the methods described in U.S. Pat. No.5,079,274.

Monoethylenically unsaturated monomers include both aliphatic andaromatic monomers. Monoethylenically unsaturated aliphatic monomerspreferably include monovinyl aliphatic monomers, for example derivativesof acrylic and methacrylic acids and acrylonitrile. The preferredmonovinyl aliphatic monomers include methyl methacrylate, acrylonitrile,ethyl acrylate, 2-hyroxyethyl methacrylate and mixtures thereof.

Monoethylenically unsaturated aromatic monomer preferably is amonovinylidene aromatic monomer. Monovinylidene aromatic monomersinclude, for example, styrene and its derivatives, such as ortho-, meta-and para-methyl styrenes, and ortho-, meta-, and para-ethyl styrenes;vinylnaphthalene; vinylbenzyl chloride and vinylbenzyl alcohol.Preferred monovinylidene aromatic monomers include styrene,vinylbenzylchloride, methylstyrene and ethylstyrene. The most preferredmonovinylidene aromatic monomer is styrene.

The polymers are preferably derived from (1) polyunsaturated monomerwhich acts as a crosslinking agent and (2) a monoethylenicallyunsaturated monomer. At least one of the polyunsaturated andmonoethylenically unsaturated monomers is aromatic, preferably both arearomatic provided that at least major portion (at least 50 percent byweight based on the total weight of monomers used) is aromatic.

Polyunsaturated crosslinking monomers include, for example, thepolyvinylidene compounds listed in U.S. Pat. No. 4,382,124. Preferredpolyunsaturated crosslinking monomers are divinylbenzene (includingcommercially available divinylbenzene containing less than about 45weight percent ethylvinylbenzene), trivinylbenzene, and ethylene glycoldiacrylate, mixtures thereof and the like. Other suitable aliphaticpolyunsaturated monomers can include divinylsulfide and such similarcompounds. While hydrocarbon monomers are preferred, the crosslinkingmonomers may also include heterocyclic compounds such asdivinylpyridine. The most preferred crosslinking monomer isdivinylbenzene.

For crosslinking, sufficient amounts of the polyunsaturated monomer mayadvantageously be used to give dimensional stability to the polymers sothat they will swell rather than dissolve in the subsequent swellingsteps. The amount of crosslinking required will depend on the polymer'sporosity characteristics desired. The percent crosslinking in thepolymer prior to post-crosslinking of the polymer is based on thatweight percent of the polymers which is attributable to thepolyunsaturated monomer. The crosslinking monomer serves to increase thephysical stability of the adsorbent. The amount of crosslinking monomerrequired depends significantly on the process conditions used to preparethe polymer and can range anywhere from about 0.1 to about 35 percent byweight of total monomer. When the crosslinking monomer is an aliphaticpolyunsaturated monomer, the amount used is less than 20 percent byweight of the total monomer. In the instances where the polymercomprises both a monoethylenically unsaturated aliphatic monomer and analiphatic polyunsaturated monomer, the amount of the two monomers doesnot exceed more than 20 percent by total weight of all the monomers.

Macroporous polymers generally may be prepared by forming a suspensionof a monomer mixture within an agitated, continuous suspending medium.The monomer mixture comprises at least one monoethylenically unsaturatedmonomer, preferably a crosslinking monomer, an effective amount of inertdiluent, and an effective amount of a free-radical polymerizationinitiator.

The inert diluent preferably acts as a solvent for the monomer but notfor the product polymer. The desired diluent will be determined by thecharacter of the monomers in the monomer mixture and the type ofporosity characteristics desired.

The inert diluents may be separated into two types depending upon thetype of swelling effect the diluent has on the polymer. Non-swellinginert diluents exert essentially no solvent action on the polymer. Suchnon-swelling diluents include alkanols with a carbon atom content offrom about 4 to about 10, and higher saturated aliphatic hydrocarbons,such as heptane, and isooctane.

The second type of inert diluent includes those which exert a swellingaction on the copolymers. Such diluents are typically employed in thepreparation of isoporous copolymer beads. Examples of such diluentsinclude solvents such as ethylene dichloride, toluene, benzene, xyleneand methylene chloride. Preferably, toluene is used as the swellinginert diluent. As a further guide in the selection of a suitablediluent, reference may be made to scientific literature, for example,Hildebrand and Scott, Solubility of Non-Electrolytes, 3rd ed., N. Y.(1950).

The term suspension polymerization is a term well known to those skilledin the art and comprises suspending droplets of the monomer or monomermixture and of the inert diluent in a medium in which neither aresoluble. This may be accomplished by adding the monomer or monomermixture and the inert diluent with any additives to the suspendingmedium which contains a dispersing or suspending agent. For theethylenically unsaturated aromatic monomers of the present invention,the suspending medium is usually water, the suspending agent, and asuspension stabilizer, e.g., gelatin, polyvinyl alcohol or a cellulosicsuch as hydroxyethyl cellulose, methyl cellulose or carboxymethyl methylcellulose. When the medium is agitated, the organic phase (monomer andporogenic solvent) disperses into fine droplets. Polymerization isinitiated by heating the suspension to a temperature of typically fromabout 50° C. to about 90° C. in the presence of a free radicalinitiator. The suspension is maintained at the polymerizationtemperature until a desired degree of conversion of monomer to copolymeris obtained. Suitable methods of suspension polymerization areillustrated in U.S. Pat. Nos. 4,419,242; 4,564,644; and 4,444,961.

The free-radical initiator may be any one or a combination ofconventional initiators for generating free radicals in thepolymerization of ethylenically unsaturated monomers. Representativeinitiators are UV radiation and chemical initiators such asazobisisobutyronitrile, benzoyl peroxide, t-butylperoctoate,t-butylperbenzoate and isopropylpercarbonate. Other suitable initiatorsare mentioned in U.S. Pat. Nos. 4,192,921; 4,246,386; and 4,283,499. Thefree-radical initiators are employed in an amount sufficient to inducepolymerization of the monomers in a particular monomer mixture. Aneffective amount will vary, as those skilled in the art can appreciate,and will depend generally on the type of initiators employed, as well asthe type and proportion of monomers being polymerized. Generally, aneffective amount is from about 0.005 to about 10 percent, and preferablyfrom about 0.025 to about 2 weight percent, based on total monomerweight.

The preferred macroporous polymer is prepared from about 1 to about 35percent by weight of divinylbenzene, with the balance being (the weightpercent of) styrene. More preferably, the macroporous polymer isprepared from about 1 to about 15 percent by weight of divinylbenzeneand most preferably from about 1 to about 10 percent by weight ofdivinylbenzene, based on the total monomer weight.

The gel polymer is prepared by suspension polymerization by methodsknown in the art and comprises from about 0.0 to about 20.0 percent byweight of divinylbenzene, with the balance being the weight percent ofstyrene. Preferably, the gel polymer is a polymer of about 0.1 to about8.0 percent by weight of divinylbenzene with the balance being styrene.

The macroporous or gel polymer is post-crosslinked in a swollen state inthe presence of a Friedel-Crafts catalyst to introduce rigidmicroporosity (pores with a diameter less than about 20 Å) into thecopolymer. Post-crosslinking of the polymer while it is in a swollenstate displaces and rearranges adjacent polymer chains, thereby causingan increase in the number of micropores. This rearrangement serves toincrease overall porosity and surface area of the copolymer, while alsodecreasing the average pore size. Post-crosslinking also serves toimpart rigidity to the polymer structure, which is useful for providingenhanced physical and dimensional stability to the polymer.

Post-crosslinking may be achieved by haloalkylating or acylating thepolymer by reacting the polymer with a polyfunctional alkylating oracylating agent, swelling the resulting haloalkylated polymer with aninert swelling agent, and thereafter maintaining the swollen,haloalkylated polymer at a temperature and in the presence of aFriedel-Crafts catalyst such that haloalkyl or acyl moieties on thepolymer react with an aromatic ring of an adjacent polymer chain to forma bridging moiety. Friedel-Crafts catalysts are Lewis acids and include,for example, AlCl₃, FeCl₃, BF₃ and HF. AlCl₃ and FeCl₃ are preferred. Inthe instances where the polymer is, for example, a polymer of styrene,vinylbenzyl chloride and divinylbenzene, the haloalkylation or acylationof the polymer is not necessary. In those instances, the polymer isswollen with an inert swelling agent and post-crosslinked in the swollencondition to obtain the bridging moieties. The post-crosslinking methodsare described in U.S. Pat. Nos. 4,191,813 and 4,263,407.

The terms microporosity, mesoporosity and macroporosity refer to thepore volume per gram of sample for each type of pore respectively, andare determined by the nitrogen adsorption method in which dried anddegassed samples are analyzed on an automatic volumetric sorptionanalyzer. The instrument works on the principle of measuring the volumeof gaseous nitrogen adsorbed by a sample at a given nitrogen partialpressure. The volumes of gas adsorbed at various pressures are used inthe B.E.T. model for the calculation of the surface area of the sample.The average pore diameter is calculated from the relationship betweenthe surface area and the pore volume of the sample, assuming acylindrical pore geometry. Micropores are pores with a diameter lessthan about 20 Å (2 nm), mesopores are pores with a diameter from 20 Å to200 Å (2 nm to 20 nm), and macropores are pores with a diameter greaterthan 200 Å (20 nm).

The pore size range or the porosity range of the porous post-crosslinkedpolymers as a substrate for the adsorbent material of the invention canbe selectively chosen depending upon the intended application of thesurface-modified adsorbent of the invention obtained therefrom, and thecomposition of the surface-modifying monomer or polymer.

In applications where adsorption capacity is a primary consideration andthe molecules to be separated are small (<800 MW) and diffusionallimitations are a consideration, the post-crosslinked polymer containing0.2 to 1.0 cc/g of micropores is preferred, with 0.4 to 0.7 cc/g ofmicropores being the most preferred. The balance of the pore volume canbe mesopores and macropores up to a total pore volume of 2.0 cc/g.

In applications where the adsorption rate is a primary consideration andthe molecules to be separated are greater than 200 MW, thepost-crosslinked polymer containing 0.2 to 0.4 cc/g of micropores, withthe balance of the pore volume being contributed by mesopores andmacropores up to a total pore volume of 2.0 c/g, is preferred.

In applications where adsorption capacity is a primary consideration andthe molecules to be separated are small (<800 MW) and diffusionallimitations are not a consideration, the post-crosslinked polymercontaining porosity of about 0.2 to 1.0 cc/g contributed by themicropores is preferred, with 0.4 to 1.0 cc/g of the porositycontributed by the micropores being the most preferred. The balance ofthe pore volume can be mesopores and macropores up to a total porevolume of 2.0 cc/g.

A porous post-crosslinked polymer substrate for the adsorbents of theinvention is described in commonly assigned pending U.S. patentapplication Ser. No. 262,820, filed Jun. 21, 1994. The porouspost-crosslinked polymer described therein is prepared from amacroporous polymer of from 45 to 80 weight percent of at least onearomatic monomer, from 0 to about 20 weight percent of a monovinylaliphatic monomer and from 20 to 35 weight percent of a polyvinylaromatic crosslinking monomer. In any given instance, the ratio of themonovinyl aromatic and aliphatic monomer to the polyvinyl aromaticcrosslinking monomer is from 1.8 to 4.0. Typically, the inert solventused in the preparation of this macroporous polymer comprises from 50 to70 weight percent and preferably from 55 to 65 weight percent of thetotal weight of the monomer mixture and the inert solvent. The totalporosity of the porous post-crosslinked polymer obtained therefrom is atleast 1.5 cc/g, with the microporosity ranging from about 0.2 to about0.4 cc/g, and comprising less than 20 percent of the total porosity. Atthe same time, the mesoporosity exceeds 0.5 cc/g with the preferredrange being between from 0.5 to 1.3 cc/g.

Surface-modified Substrate Polymer

The surface-modified adsorbents of the invention can generally beprepared by a two-step process. The first step involves selectiveincorporation of a polymerizable monomer or a polymer into themicropores of the porous post-crosslinked polymer substrate and thesecond step involves the immobilization of the polymerizablesurface-modifying monomer or the polymer onto the post-crosslinkedpolymer substrate.

The term "incorporation" as used herein refers to imbibing or adsorbingthe surface-modifying polymer or monomer onto the porouspost-crosslinked substrate polymer. It also refers to precipitating outthe surface-modifying polymer or monomer from its solution onto theporous post-crosslinked substrate polymer.

The incorporation of the surface-modifying monomer or polymer onto theporous post-crosslinked polymer can be accomplished by various methods.In one method, a solution of a polymerizable monomer or a polymer may beadsorbed onto the post-crosslinked substrate by continuous addition ofthe solution onto the porous post-crosslinked substrate polymer.

The efficiency of the adsorption can be optimized by a proper choice ofthe solvent for the surface-modifying monomer or the polymer. Water, anyorganic solvent, or a mixture of water and one or more organic solventscan be used to dissolve the surface-modifying monomer or the polymer.Illustrative of the organic solvents include hexane, isooctane, dodecaneand aliphatic ethers. As a further guide in the selection of a suitablesolvent, reference may be made to scientific literature, for example,Hildebrand and Scott, Solubility of Non-Electrolytes, 3rd ed., N. Y.(1950).

A primary consideration in choosing the solvent is that there is asignificant driving force for the adsorption of the surface-modifyingmonomer or the polymer onto the surface of the substrate polymer. Thedriving force for this adsorption can be a difference in hydrophilicityof the post-crosslinked polymer substrate and the solvent. See, forexample, A. Ben-Naim, Hydrophobic lnteractions, Plenum Press, New York(1980).

The concentration of the surface-modifying monomer or the polymer insolution varies depending on its solubility, the molecular weights ofthe surface-modifying monomer or the polymer, the pore distribution andthe pore volume of the post-crosslinked polymer substrate. Theconcentration of the surface-modifying monomer or the polymer in theaqueous or organic solvent ranges from about 1 ppm to about 50 weightpercent by weight of the solution. The surface-modifying monomer or thepolymer can be gradually added to the post-crosslinked substrate at arate which is slower than the rate of the adsorption of thesurface-modifying monomer or the polymer thereto.

In another method, the surface-modifying polymerizable monomer or thepolymer can also be adsorbed from the vapor phase and condensed onto thepost-crosslinked polymer.

Still another method of incorporating a surface-modifying monomer or apolymer involves precipitation of the surface-modifying monomer or thepolymer from its solution onto the porous crosslinked polymer substrate,for example, by changing the solvent polarity or pH by methods known toone skilled in the art.

The second step in the preparation of the surface-modifiedpost-crosslinked adsorbents of the invention involves immobilization ofeither the surface-modifying monomer or the polymer onto the substratepolymer.

The immobilization of the surface-modifying monomer or the polymer canbe accomplished by polymerizing and crosslinking the surface-modifyingmonomer or the polymer in situ with the functional groups present in thepost-crosslinked polymer substrate. The immobilization may also beachieved by grafting the surface-modifying monomer or the polymer to thesubstrate polymer using the functional groups present both in thesubstrate polymer and surface-modifying polymers and monomers. Anexample of a functional group on the substrate polymer that can be usedin grafting is a residual chloromethyl functionality, which readilyreacts with a broad variety of functional groups in thesurface-modifying monomer or polymer. The polymerization, crosslinkingand grafting of the polymerizable surface-modifying monomer or thepolymer onto the substrate polymer is achieved by methods known in theart.

An important aspect of the invention is that, depending on the intendedapplication, polymeric adsorbents of the invention can be preparedwithout substantially altering the porosity, water retention capacity,and pore structure of the substrate polymer by properly choosing thesynthesis conditions of the substrate polymer and surface-modifyingpolymers.

Although it is not intended to limit the invention to any theory, it isbelieved that the substrate polymer is in a relaxed state because ofbeing post-crosslinked in the swollen state, i.e., it is pre-swollen ordissolved in a thermodynamically good solvent before the bridgingreaction occurs. After the post-crosslinking, the alkylene bridges areformed between the polymer chains. These rigid bridges weaken theinteraction between polymer chains by hindering the chains fromapproaching each other upon removal of the solvent. A considerablefraction of the polymer chains in post-crosslinked polymers areavailable for solvation by a wide variety of molecules. This phenomenongives the post-crosslinked polymer an affinity for a wide variety ofmolecules because the open "pre-swollen" network is available forinteraction with a variety of molecules and does not require a largeenthalpic contribution in order to swell the post-crosslinked polymersubstrate. Consequently, materials that usually do not possess similarsolubility character or solubility parameter as the styrenic polymersadsorb readily onto the porous post-crosslinked polymer. It is believedthat this phenomenon eliminates the need for the substrate polymer andthe surface-modifying monomer or polymer to have similar solubilitycharacteristics or solubility parameters in order to achieve molecularinterpenetration.

The process of the invention for preparing the adsorbent materials fromthe porous post-crosslinked polymer substrate offers versatility inproducing an almost unlimited variety of chemical modifications to thepost-crosslinked polymer's internal surface and pores. The choice ofsurface-modifying polymerizable monomer or polymer and the method forthe immobilization thereof onto the post-crosslinked polymer substratedepend on the desired application of the resulting polymeric adsorbents.Any given polymerizable monomer or a polymer may be used to obtain thesurface-modified post-crosslinked polymeric adsorbents of the invention.The surface-modifying polymers may be either optically active ornon-optically active.

In the process of the invention, during the continuous addition of thepolymerizable surface-modifying monomer or the polymer onto thesubstrate polymer, smaller micropore domains of the substrate polymerare filled first. These smaller micropores, after filling, becomeinaccessible and are not useful in later separation or synthesisprocesses. By selectively filling the micropore domains and immobilizingthe initial surface, modifying the monomer or polymer therein, it ispossible to immobilize subsequent surface-modifying monomers or polymersinto the remaining larger pores of the substrate polymer.

The subsequent surface modification of the adsorbent polymers of theinvention is accomplished by using reactive sites incorporated into thesubstrate polymer via the initial surface-modifying monomer or polymer.Thus, various chemical reactive compounds can be selectively locatedinto the various pore domains of the substrate polymer.

The actual amount of the surface-modifying monomer or polymer in theadsorbent will vary depending on the physicochemical properties of thesurface-modifying polymer, the pore distribution of the substratepolymer and the degree of crosslinking and post-crosslinking in thesubstrate polymer. Typically, the maximum amount of thesurface-modifying monomer or polymer is the amount necessary to fillpores less than 100 Å and produce a monolayer or a thin film of thepolymer on the macropores of the resulting adsorbent. The minimum amountof the surface-modifying monomer or polymer is the amount necessary toprovide sufficient functionality for the desired application.

The weight ratio of the surface-modifying polymerizable monomer(s) orpolymer(s) to the porous post-crosslinked polymer substrate caneffectively range from about 0.01:1 to about 1.5:1. Preferably, theratio varies from about 0.05:1 to about 0.8:1.

The polymeric adsorbent materials of the invention are useful forseparation of solutes from solutions, as chromatographic packingmaterials in chromatographic separation systems, as catalysts forchemical processing, as ion exchange resins when appropriatelyfunctionalized, for separation of proteins, for resolution of racemicmixtures, as asymmetric templates in enantioselective transformation andthe like.

The adsorbent materials of the invention may be particularly useful inthe separation of compounds via chromatography. For these applications,the adsorbents may be prepared from either optically active ornon-optically active, surface modifying polymers. Non-optically activepolymers do not rotate the plane of polarized light. Typical surfacemodifying polymers of the non-optically active type include polymersprepared from acrylates, methacrylates, and/or styrenics. Included arepolymers prepared from such compounds as butyl acrylate, methylmethacrylate, allyl methacrylate, methacrylic acid, styrene, andfunctionalized styrenes such as vinylbenzylchloride.

The above non-optically active, surface modifying polymers arecopolymerized by routine procedures well-known in the art. Theseprocedures are described below in relation to optically active polymers.Subsequent incorporation and immobilization of the non-optically activepolymers are also accomplished in a similar manner to that of opticallyactive polymers described below.

The adsorbent materials of the invention are also particularly useful inthe resolution of racemic mixtures and as asymmetric templates inenantioselective synthesis. For these applications, the adsorbentstypically comprise an optically-active polymer as surface-modifyingpolymers.

Optically active polymers contain asymmetric centers in the main chainand/or side chains; see for example, A. Abe and K. Inomata, "OpticallyActive Polymers", in Polymer Handbook, 3rd Ed., Wiley Interscience, ppVII 561-Vii/575 (1980). Any hydrophobic, hydrophilic (ionic), oramphiphilic optically active polymer can be immobilized onto the surfaceof the post-crosslinked polymer substrate. Alternatively, an opticallyactive monomer or a mixture of an optically active monomer with otheroptically active monomer or optically inactive monomer can be adsorbedonto the surface of the substrate polymer and immobilized bypolymerizing, crosslinking or grafting as described above.

An example of optically-active polymers useful in the present inventionare described in U.S. Pat. No. 5,435,919.

The optically active polymers described in the above-mentionedapplications are amphiphilic, water-soluble copolymers comprising ahydrophobic component having a chiral moiety and a hydrophilic componenthaving an ionic group. Preferably, the optically active polymer furthercomprises an achiral hydrophobic component. The hydrophilic componentmay be a monomer which already contains the ionic species or whichcontains a precursor functionality which can be readily converted intoionic species. Examples of precursor groups which can be readilyconverted into cationic species are reactive halides which can reactwith neutral nucleophiles to produce cationic groups. Preferred cationicprecursor functionalities are pendant benzyl halides which are capableof reacting, for example, with ammonia or dimethyl sulfide to producethe unsubstituted ammonium or dimethyl sulfonium cations, respectively,e.g., ##STR1## or are amines or sulfides which are capable of reactingwith alkyl halide to produce a substituted ammonium or sulfonium cation,e.g., ##STR2##

Examples of preferred anionic precursor functionalities are thecarboxylic acids and sulfonic acids which are readily ionized underalkaline conditions to the preferred carboxylate and sulfonate anions.

The hydrophilic component containing either the ionic group or asynthetic precursor to the ionic group is preferentially incorporatedinto the polymer by copolymerization with unsaturated monomerscontaining the desired functionality. The preferred unsaturated monomersare of the styrenic, acrylic or methacrylic type. The acrylic andmethacrylic type monomers are inclusive of the corresponding acids,esters and amides. Suitable styrenic monomers include, for example,styrene sulfonic acid sodium salt, vinylbenzoic acid andvinylbenzyl-chloride (VBC). Suitable acrylic or methacrylic monomersinclude, for example, methacrylic acid,2-acrylamido-2-methyl-l-propanesulfonic acid (AMPS),2-acrylamidoglycolic acid, and 2-(dimethylamino)ethyl methacrylate.

Alternatively, a portion of the aromatic rings in unsubstitutedpolystyrene may be directly functionalized, e.g., by sulfonation or bychloromethylation followed by amination.

The hydrophilic monomeric component generally comprises from 25 to 80weight percent of the total monomer employed to produce the desiredpolymeric surfactant, preferably from 30 to 60 weight percent.

The optically active polymeric materials preferably contain ahydrophobic component which carries the chiral functionality. Thehydrophobic component is preferentially incorporated into the polymer bycopolymerization with an ethylene-type monomer, preferably anoptically-active ethylene-type monomer. Suitable optically-activeethylene-type monomers include the following: chiral alkenes, such asβ-pinene and limonene; substituted chiral alkenes, such as1-penten-3-ol; chiral vinyl ethers and esters, such as vinyl sec-butylether and vinyl 2-alkoxy- or 2-aryloxypropionates; and chiral esters andamides of acrylic, methacrylic and vinylacetic acids, such as menthylmethacrylate, bornyl acrylate, cholesteryl vinylacetate andN-(1-phenylethyl) methacrylamide. The preferred chiral monomers are theoptically-active esters and amides of acrylic and methacrylic acids.

These optically-active unsaturated monomers can be produced by routinemethods well known to those of ordinary skill in the art. For example,the preferred optically-active esters and amides of acrylic andmethacrylic acids can be prepared by the reaction of the appropriateunsaturated acid chloride with an optically-active alcohol or amine.Preferred chiral alcohols include terpene-derived alcohols like menthol,borneol and α-terpineol; steroid-derived alcohols like cholesterol; andsecondary alcohols like α-methyl benzyl alcohol. Preferred chiral aminesinclude primary amines of secondary alkyl groups like a-methyl benzylamine, 2-amino-l-alkanols derived from α-aminoacids like alaninol, andprimary amines derived from terpenes like bornylamine.

The hydrophobic monomeric component generally comprises from 3 to 70weight percent of the total monomer employed to produce the desiredpolymeric surfactant, preferably from 10 to 50 weight percent.

The optically active polymers may also include an achiral, hydrophobiccomponent. Optionally, the achiral, hydrophobic component can containpolymerizable groups which allow a limited amount of crosslinking. Toomuch crosslinking may adversely affect the water solubility of theresulting polymeric surfactant. The achiral hydrophobic component ispreferentially incorporated into the optically active polymer bycopolymerization with achiral unsaturated monomers. Suitable achiralunsaturated monomers include the following: alkenes, such as propyleneand butadiene; styrene and substituted styrenes, such ast-butyl-styrene, α-methyl-styrene and divinylbenzene; ester and amidederivatives of acrylic and methacrylic acids, such as ethyl acrylate,acrylamide, methyl methacrylate, lauryl methacrylate, allyl methacrylateand 2-hydroxyethyl methacrylate; vinyl ethers and esters, such as alkylvinyl ethers and vinyl alkanoates; and vinyl nitriles, such asacrylonitrile.

The hydrophobic achiral monomeric component generally comprises from 0to 62 weight percent of the total monomer employed to produce thedesired polymeric surfactant, preferably from 15 to 55 weight percent.Any vinyl-addition crosslinkable component, e.g., allyl methacrylate, islimited to 10 weight percent or less of the monomer employed to producethe desired polymeric surfactant, preferably less than 3 weight percent.

The copolymerizations of the above-described monomers are typicallyachieved by routine procedures well known to those skilled in the art.For example, for terminally unsaturated monomers which are the preferredstarting materials for the optically active polymers, copolymerizationis accomplished by free radical polymerization of the vinyl groups ofthe monomers. Thus, for example, the monomeric components are contactedtogether under an inert atmosphere with a free radical initiator in thepresence of an inert organic solvent under conditions which affordpolymerization, typically elevated temperatures and a nitrogenatmosphere. If a monomer which serves as a precursor to the ionicfunctionality was originally employed in the polymerization, theresulting reaction mixture is further contacted with the appropriatereagent under conditions which convert the precursor into the ionicfunctionality. The desired polymers are isolated by conventionalprocedures. Often it is most convenient to isolate the product as anaqueous solution.

The optically active polymers described above are immobilized on theporous post-crosslinked polymer substrate by the methods described aboveto obtain optically active adsorbents of the present invention. Theoptically active polymer can be nonpolar, polar, cationic, anionic, orzwitterionic, depending on the choice of monomers. Preferred cationicgroups are substituted sulfonium -S⁺ R₂ groups and substituted ammonium-N⁺ R₃ groups. R is preferably methyl. Preferred anionic groups arecarboxylate and sulfonate groups.

The optically active surface-modified polymeric adsorbents are usefulfor resolution of racemic mixtures and as asymmetric templates inenantioselective transformations. While it cannot always be easilypredicted which enantiomer of the racemic mixture will preferentiallyinteract with the optically active polymer in a particular resolutionprocess, the result can be easily determined by routine experimentation.Both the configurations of the optically-active copolymer are equivalentin their resolving power so that replacement of one configuration withthe other results in the preferential interaction with the otherenantiomer of the racemic mixture.

In a typical experiment, a solution of the racemic mixture to beresolved is added to the optically active polymeric adsorbent of theinvention. The resulting mixture is stirred or shaken in order toincrease the rate of complexation, and the liquid phase is easilyseparated by decantation or filtration. Effective resolution of theracemic mixture can be achieved by multistage operation if nosignificant enantiomeric enrichment per unit operation occurs.

The following examples serve to illustrate the invention. Surface area,pore size, and porosity were determined on a Quantachrome ModelAutosorb-1 nitrogen adsorption analyzer by measuring the volume ofgaseous nitrogen adsorbed by a sample at a given nitrogen partialpressure and by conducting the appropriate calculations according to theB.E.T. model.

EXAMPLE 1

A post-crosslinked polymer was prepared from a gel copolymer of 1.5weight percent divinylbenzene and 98.5 weight percent styrene by aprocedure described in U.S. Pat. No. 5,079,274.

EXAMPLES 1a-1e

The polymeric adsorbents of the invention were prepared by adding 100grams (g) (45 g dry) of wet post-crosslinked polymer produced fromExample 1 to each of 5 pint bottles.

The beads were slurried by adding 125 ml of deionized water. Ethyleneglycol dimethacrylate (EGDM) containing 0.20 weight percentt-butylperoctoate initiator was added to the 5 pint bottles in theamounts of 1.0, 2.0, 4.0, 8.0 and 16.0 grams, respectively. Thecontainers were capped and placed on a shaker bath and heated to 70° C.for 21 hours. After polymerization each sample was rinsed with 10 bedvolumes of methanol and 10 bed volumes of water to remove any residualmonomers. Similarly, the beads were extracted with methylene chloride toremove residual monomers.

EXAMPLE 2

A porous post-crosslinked polymer was produced from a macroporouscopolymer prepared from 6.0 percent by weight of divinylbenzene and 94weight percent of styrene according to a procedure described in GermanPat. No. DD 249,274 A1. The post-crosslinked polymer is thenfunctionalized by aminating the chloromethyl groups with dimethylamine.

FIG. 1 illustrates the transmission electron micrograph of the polymer.

EXAMPLE 2a

The polymeric adsorbent beads were prepared by adding 4.34 g ofpolyamide (melting temperature of the polymer TM=95° C.) and 60 ml ofm-cresol to a 3-neck 1 liter round-bottom flask equipped with stirrer,reflux condenser and heating mantle. The mixture was heated to 100° C.to dissolve the polyamide. Next 300 milliliter (mL) of deionized waterwere added to the flask and the mixture cooled to 60° C. While agitatingvigorously, 134 g of wet (58.2 g dry) aminated post-crosslinked polymerof Example 2 were added to the flask. The vessel was heated at 97° C.for 20 hours. The adsorbent polymer was transferred to a fritted columnand the m-cresol was extracted from the beads with 1500 mL of2-propanol.

EXAMPLES 3a and 3b

The polymeric adsorbent beads were prepared essentially by the proceduredescribed in Example 2a except 4.34 g and 11.32 g, respectively, ofNylon 6 were substituted for the polyamide.

FIGS. 2 and 3 illustrate the transmission electron micrograph of thepolymeric adsorbents prepared by these examples.

EXAMPLE 4a

Eight grams of an epoxy resin DER® 732, commercially available from TheDow Chemical Company, were added to a beaker containing 300 mL of a 25percent propanol-water solution. While stirring vigorously 100 g of wetaminated post-crosslinked polymer of Example 2 was added to the beaker.Stirring was continued for six hours. The polymeric adsorbent wasbackwashed with a copious quantity of deionized water for 1 hour.

EXAMPLE 4b

The adsorbent was prepared as described in Example 4a. The adsorbent wastransferred to a 3-necked round-bottom flask equipped with stirrer,reflux condenser and heating mantle. 0.9 mL of diethylene triamine wasadded to the adsorbent and deionized water slurry. The mixture washeated to 60° C. for 6 hours.

FIG. 4 illustrates the transmission electron micrograph of the adsorbentof this example.

EXAMPLE 5a

The adsorbent was prepared in essentially the same manner as describedin Example 4a, only 10 g of an epoxy resin DER® 331, commerciallyavailable from The Dow Chemical Company, was substituted as the epoxyresin.

EXAMPLE 5b

The adsorbent was prepared from the adsorbent of Example 5a in the samemanner as Example 4b was prepared from Example 4a above.

EXAMPLE 6

A porous post-crosslinked polymer of Example 2 prior to amination,containing residual chloromethyl groups was aminated in a 1-liter parrreactor using a large molar excess of methylamine. The excess amine wasremoved from the adsorbent by washing with dilute hydrochloric acidfollowed by dilute sodium hydroxide and deionized water. FIG. 5illustrates the transmission electron micrograph of the aminated porouspost-crosslinked polymer.

EXAMPLE 6a

2.73 Grams of epoxy silicone UV9320, available from General Electric,along with 300 mL of a 25 percent propanol-water solution was added to a1 liter 3-necked round-bottom flask equipped with stirrer, refluxcondenser and heating mantle. While stirring vigorously, 65 g of the wetpolymer from Example 6 was added to the flask. Stirring was continuedfor six hours. The resin was backwashed with a copious quantity ofdeionized water for 1 hour.

FIGS. 6 illustrates the transmission electron micrographs of Example 6a.

EXAMPLE 7

Preparation of the Substrate Polymer

A porous post-crosslinked polymer substrate was prepared by the methoddescribed in Example 1 of pending U.S. patent application Ser. No.262,820, filed Jun. 21, 1994. The method is as follows:

A monomer mixture consisting of styrene (201.5 g), divinylbenzene (DVB,241.8 g, 55 weight percent active, 30 weight percent based on monomercharge), toluene (856 g, 65.9 weight percent based on total organicload), t-butylperoctoate (5.32 g, 50 weight percent active) andt-butylperbenzoate (1.51 g) was added to an aqueous solution (1300 g),containing 0.2 weight percent carboxymethyl methyl cellulose and anaqueous phase polymerization inhibitor in an automated 3.785 liters (L)stainless steel reactor. The reactor was sealed, purged with nitrogenand the agitation started to size the monomer. After 45 minutes ofsizing, the temperature was raised to 80° C. for 7 hours and then raisedto 110° C. for 5 hours. After cooling to room temperature, the reactormass was dumped and washed thoroughly to remove the suspending agents.The wet polymer beads were steam stripped to remove the toluene and thenair dried overnight.

The dried polymer (50 g) was transferred into a 1-L jacketed glassreactor equipped with a stirrer, temperature controller and a condenser.Monochloromethyl methyl ether (500 mL)) was added and the agitationstarted. After about 30 minutes of swelling at room temperature,anhydrous ferric chloride (15 g) was added and reaction temperatureslowly ramped to 52° C. and held constant for 3 hours. Thechloromethylated beads (CMPS) after separation from the liquor, werewashed 3 times with methanol to destroy the unreacted ether and toremove the entrained catalyst.

The methanol wet CMPS from above were washed 3 times with ethylenedichloride to remove most of the methanol and then transferred into a1-L jacketed glass reactor equipped with a stirrer, temperaturecontroller and distillation column. The reactor was then heated to 83°C. to distill any remaining methanol. After cooling, a reflux condenserwas added to the reactor and ferric chloride (15 g) was added. Thereactor temperature was slowly ramped to 80° C. and held constant for 3hours. The methylene-bridged CMPS after separation from the liquor, werewashed 3 times with methanol to remove the catalyst and ethylenedichloride followed by deionized water until free of acid.

EXAMPLES 8-18

Examples 8-18 illustrate the preparation of the optically active polymerimmobilized in the porous post-crosslinked macroporous polymer substrateto obtain optically active polymeric adsorbents of the invention, andthe applications thereof in the enantioselective synthesis andresolution of racemic mixtures.

EXAMPLE 8

Nonpolar Optically Active Polymer Immobilized on Post-crosslinkedMacroporous Copolymer

This example illustrates preparation of a subsequent surfacemodification of an initially surface-modified adsorbent polymer of theinvention, carried out in two stages.

A 100-mL three-necked round-bottom flask was equipped with a nitrogeninlet, a reflux condenser connected to an oil bubbler with a nitrogenoutlet, and a mechanical air-driven stirrer. The flask was immersed intoan oil bath and a nitrogen atmosphere was established. 10 Grams of wetporous post-crosslinked polymer of Example 2 prior to amination, 20 mLwater, and 0.8 g of tetrahydrofuran were placed into the flask, followedby 0.18 g methyl methacrylate, 0.18 g allyl methacrylate, and 3.6 mg2,2'-azo-bis(isobutyronitrile), available under the Tradename VAZO-64from dupont. The mixture was heated at 85° C. for 3 hours with slowmechanical stirring. The surface-modified adsorbent thus obtained wassubsequently surface-modified with an optically active polymer asdescribed below.

A mixture of (L)-menthyl methacrylate (1.5 g) and methyl methacrylate(1.0 g) was added by a syringe pump at 85° C. for 12 hours, constantlymaintaining the nitrogen atmosphere to the surface-modified polymerobtained above. The resulting mixture was then cooled, the liquid phaseremoved, and the resulting subsequent surface-modified polymericadsorbent was washed several times with chloroform. Analysis of theliquid phase and washings on the percentage of solids indicated that thepercentage of the optically active polymer immobilized on themacroporous polymer is about 95 percent.

EXAMPLES 9-13

The initial surface-modified polymers obtained in Example 8 were used toimmobilize subsequent nonionic optically-active polymers thereon by themethod described in Example 8. The substrate polymer used in Examples9-12 for initial surface modification is that of Example 2 prior toamination. The substrate polymer used in Example 13 for initial surfacemodification is that of Example 7.

Table I sets forth the respective compositions of monomers used in thesubsequent surface modification.

                  TABLE I                                                         ______________________________________                                        Nonionic Optically-Active Polymers                                            Immobilized on Initial Surface-Modified                                       Polymers of Example 8                                                                 Subsequent Surface-Modifying Monomers                                         (Weight Percent)                                                      Example   (L)-MnMA      (L)-PMA  MMA                                          ______________________________________                                         9        70            --       30                                           10        --            80       20                                           11        --            50       50                                           12        30            --       70                                           13        60            --       40                                           ______________________________________                                         (L)-PMA = (L)1-phenylethyl methacrylamide                                     (L)MnMA = (L)menthyl methacrylate                                             MMA = methyl methacrylate                                                

EXAMPLE 14

Anionic Optically-active Polymer Immobilized on Post-crosslinkedMacroporous Copolymer

A 100-mL three-necked round-bottom flask was equipped with a nitrogeninlet, a reflux condenser connected to an oil bubbler with a nitrogenoutlet, and a mechanical stirrer. The flask was immersed into an oilbath and a nitrogen atmosphere was established. The porouspost-crosslinked polymer of Example 2 prior to amination (10 g of wetresin), water (20 mL), and tetrahydrofuran (0.8 g) were placed into theflask, followed by the methyl methacrylate (0.18 g), allyl methacrylate(0.18 g), and VAZO™ 64 (3.6 mg). This mixture was heated at 85° C. for 3hours with slow mechanical stirring. After this, the mixture of(L)-menthyl methacrylate (1.0 g), methyl methacrylate (0.75 g), andmethacrylic acid (0.75 g) was added by a syringe pump at 85° C. for 12hours, constantly maintaining the nitrogen atmosphere. The resultingmixture was cooled, the liquid phase was removed, and the resultingpolymeric adsorbent was washed several times with chloroform ortetrahydrofuran. Analysis of the liquid phase and washings on thepercentage of solids indicated that the percentage of the opticallypolymer immobilized on the post-crosslinked polymer is about 95 percent.

EXAMPLE 15

(L)-Menthyl Methacrylate Containing Cationic Optically Active PolymerImmobilized on Post-crosslinked Macroporous Copolymer

A 250-mL three-necked round-bottom flask was equipped with a nitrogeninlet, a reflux condenser connected to an oil bubbler with a nitrogenoutlet, and a mechanical air-driven stirrer. The flask was immersed intoan oil bath and a nitrogen atmosphere was established. A porouspost-crosslinked polymer of Example 2 prior to amination, (30 g of wetresin), water (60 mL), and tetrahydrofuran (2.4 g) were placed into theflask, followed by the methyl methacrylate (0.54 g), allyl methacrylate(0.54 g), and VAZO™ 64 (10.8 mg). This mixture was heated at 85° C. for3 hours with slow mechanical stirring. After this, the mixture of(L)-menthyl methacrylate (3.0 g), methyl methacrylate (2.25 g), andvinyl benzylchloride (2.25 g) was added by a syringe pump at 85° C. for12 hours, constantly maintaining the nitrogen atmosphere. The resultingmixture was cooled, the liquid phase was removed, and the resultingpolymeric adsorbent was washed several times with chloroform ortetrahydrofuran. Analysis of the liquid phase and washings on thepercentage of solids indicated that the percentage of the opticallyactive polymer immobilized on the post-crosslinked polymer is about 90percent.

The adsorbent polymer obtained was placed into a 250 mL three-neckedround-bottom flask equipped with a reflux condenser and a mechanicalair-driven stirrer. Tetrahydrofuran (55 mL) was added to this solution,followed by methyl sulfide (1.5 mL). The resulting mixture was stirredat 35° C. for 16 hours and at 45° C. for additional one hour. Afterthis, water (50 mL) was added and unreacted methyl sulfide andtetrahydrofuran were removed by rotary-evaporation.

EXAMPLE 16

(L)-1-Phenylethyl Methacrylamide Containing Cationic Optically ActivePolymer Immobilized on Post-crosslinked Macroporous Copolymer

The procedure of Example 15 was repeated except a solution of(L)-1-phenylethylmethacrylamide (3.0 g), methyl methacrylate (2.25 g),and vinylbenzylchloride (2.25 g) in tetrahydrofuran (2 mL) was used toprepare the optically active polymer of the invention. Analysis of theliquid phase and washings on the percentage of solids indicated that thepercentage of the optically active polymer immobilized on thepost-crosslinked polymer substrate is about 90 percent. The adsorbentwas treated in the same manner as in Example 15.

EXAMPLE 17

This example illustrates enantioselective reduction of a ketone.

A solution of phenyl- 1-(2-phenylethyl)-4-piperidyl!-ketone (0.10 g) intetrahydrofuran (0.40 g) was added to wet surface-modified adsorbent ofExample 10 (1.0 g) in excess aqueous NaOH pH 9.0 (2.0 mL). This mixturewas stirred at ambient temperature for 30 minutes. After this, NaBH₄ (20mg) was added and the resulting mixture was stirred at ambienttemperature for 16 hours. The liquid phase was then decanted and theadsorbent was washed with tetrahydrofuran in order to quantitativelyextract all product from the resin. The tetrahydrofuran washings werecombined with liquid phase and analyzed by chiral High Pressure LiquidChromatography (HPLC) using a Chiracel OD-R column commerciallyavailable from Chiral Technologist Incorporation and 1.0 M aqueousNaClO₄ /acetonitrile (60/40 by volume) as a mobile phase. The productα-phenyl- 1-(2-phenylethyl)!-4-piperidinemethanol of a moderateenantiomeric purity (enantiomeric excess of S (-)=25 percent) wasobtained.

EXAMPLE 18

This example illustrates resolution of racemic alcohols.

A solution of racemic (±)-α-phenyl-1-(2-phenylethyl)!-4-piperidinemethanol (0.30 g) intetrahydrofuran/aqueous NaOH pH 11.0 (50/50 by weight; 12 mL) was addedto (0.5 g) wet surface-modified adsorbent of Example 11. The resultingmixture was stirred at ambient temperature for 30 minutes. The liquidphase was then decanted and analyzed by chiral HPLC under conditionsdescribed in Example 15. HPLC showed that the liquid phase contained45.6 percent (137 mg) of the starting alcohol, and it had moderateenatiomeric purity (entantiomeric excess of S(-)=18 percent). In a testexperiment, the racemic (±)-α-phenyl-1-(2-phenylethyl)!-4-piperidinemethanol was analyzed by chiral HPLCunder identical conditions, and no enantioselectivity was observed(peaks corresponding to single alcohol enantiomers showed the same areaof 50.0+0.1 percent).

The water retention capacities, water volumes, and the pore volumedistribution, as determined by BET nitrogen adsorption, of theadsorbents and those of the porous post-crosslinked polymer substrateswere measured and are listed in Table II. The different values for waterretention capacities of the substrate polymer of Example 2, namely 1.3and 1.43, are due to lot to lot variation in the preparation of thepolymer. Porosity of the surface-modified adsorbent of the aboveexamples is compared with its respective porous post-crosslinked polymersubstrate and percent porosity reduction calculated. The percentporosity reduction is the loss in pore volume due to the filling of thepores of the porous post-crosslinked polymer by the surface-modifyingpolymer.

                                      TABLE II                                    __________________________________________________________________________    Water Retention Capacities and Pore volume Distribution or                    Surface-Modified Post-crosslinked Adsorbents                                  Surface-Modifying                                                                            Water                                                          Polymer Expressed                                                                            Retention                                                                          CC Water                                                                           PORE SIZE RANGE (Å)                                   as g/g* of Dry                                                                          Capacity                                                                           per Gram                                                                           <8 Å                                                                          <20 Å                                                                         20-100A                                                                            >100                                                                              Total                               Example                                                                            Substrate Polymer                                                                       (Wt. %)                                                                            Adsorbent                                                                          (cc/g)                                                                            (cc/g)                                                                            (cc/g)                                                                             (cc/g)                                                                            (cc/g)                              __________________________________________________________________________    1    substrate polymer                                                                       55.0 1.22 0.05                                                                              0.48                                                                              0.24 0.01                                                                              0.73                                1a   0.022* EGDM                                                                             56.9 1.32 0.02                                                                              0.47                                                                              0.21 0.01                                                                              0.68                                     percent reduction                                                                            +8.18                                                                              (50)                                                                              (2.7)                                                                             (13.9)                                                                             (11.1)                                                                            (6.43)                              1b   0.044* EGDM                                                                             55.7 1.26 0.03                                                                              0.48                                                                              0.18 0.01                                                                              0.67                                     percent reduction                                                                            +3.03                                                                              (26.1)                                                                            (0.6)                                                                             (23.5)                                                                             (22.2)                                                                            (8.35)                              1c   0.089* EGDM                                                                             62.2 1.65 0.02                                                                              0.50                                                                              0.22 0.01                                                                              0.73                                     percent reduction                                                                            -34.8                                                                              (47.8)                                                                            +2.3                                                                              (6.7)                                                                              0   (0.68)                              1d   0.178* EGDM                                                                             60.6 1.54 0   0.48                                                                              0.19 0.01                                                                              0.68                                     percent reduction                                                                            +25.9                                                                              (100)                                                                             (1) (18.5)                                                                             (11.1)                                                                            (6.84)                              1e   0.356* EGDM                                                                             43.0 0.75 0   0   0    0.00                                                                              0.00                                     percent reduction                                                                            (38.3)                                                                             (100)                                                                             (100)                                                                             (100)                                                                              (88.9)                                                                            (99.86)                             2    subsrate polymer                                                                        56.6 1.30 0.16                                                                              0.41                                                                              0.11 0.53                                                                              1.04                                     aminated with                                                                 dimethylamine                                                            2a   0.075* Polyamide    0.15                                                                              0.33                                                                              0.08 0.51                                                                              0.92                                     percent reduction   (10.4)                                                                            (19)                                                                              (25) (3.6)                                                                             (11.9)                              2    substrate polymer                                                                       56.6 1.30 0.16                                                                              0.41                                                                              0.11 0.53                                                                              1.04                                     aminated with                                                                 dimethylamine                                                            3a   0.075* Nylon 6                                                                          54.1 1.18 0.13                                                                              0.32                                                                              0.08 0.47                                                                              0.87                                     percent reduction                                                                            (9.59)                                                                             (23.8)                                                                            (22.2)                                                                            (25.9)                                                                             (9.9)                                                                             (16.41)                             3b   0.198* Nylon 6                                                                          49.1 0.97 0.07                                                                              0.19                                                                              0.05 0.40                                                                              0.63                                     percent reduction                                                                            (26.0)                                                                             (57.3)                                                                            (53.3)                                                                            (57.1)                                                                             (24.8)                                                                            39.35                               2    substrate polymer                                                                       58.9 1.43 0.17                                                                              0.42                                                                              0.13 0.55                                                                              1.11                                     aminated with                                                                 dimethylamine                                                            4a   0.243* DER ® 732                                                                    48.8 0.95 0.03                                                                              0.15                                                                              0.08 0.48                                                                              0.72                                     Epoxy                                                                         percent reduction                                                                            (33.5)                                                                             (83.1)                                                                            (63.2)                                                                            (41.4)                                                                             (11.2)                                                                            (34.57)                             4b   0.243*    48.7 0.95 0.02                                                                              0.11                                                                              0.05 0.38                                                                              0.54                                     DER ® 732/DETA**                                                          percent reduction                                                                            (33.8)                                                                             (88.6)                                                                            (74.9)                                                                            (61.7)                                                                             (30.9)                                                                            (51.31)                             __________________________________________________________________________     DETA** Diethylenetriamine                                                

    2    substrate polymer                                                                       58.9 1.43 0.17                                                                              0.42                                                                              0.13 0.55                                                                              1.11                                     aminated with                                                                 dimethylamine                                                            5a   0.243* DER ® 331                                                                    50.8 1.03 0.09                                                                              0.22                                                                              0.09 0.58                                                                              0.88                                     percent reduction                                                                            (27.9)                                                                             (47)                                                                              (46.5)                                                                            (35.3)                                                                             +4.5                                                                              (19.64)                             5b   0.243 DER ®                                                                         47.8 0.92 0.76                                                                              0.21                                                                              0.07 0.47                                                                              0.75                                     331/DETA                                                                      percent reduction                                                                            (36.1)                                                                             (54.2)                                                                            (50.6)                                                                            (51.1)                                                                             (14.5)                                                                            (32.58)                             2    substrate polymer                                                                       55.9 1.27 0.18                                                                              0.46                                                                              0.10 0.42                                                                              0.98                                     aminated with methyl                                                          amine                                                                    6a   0.095* G.E. Silicone                                                                    52.1 1.09 0.14                                                                              0.37                                                                              0.10 0.42                                                                              0.88                                     percent reduction                                                                            (14.2)                                                                             (25.3)                                                                            (20.1)                                                                            +1   (0.2)                                                                             (9.53)                              2    substrate polymer                                                                       57.9 1.375                                                                              0.206                                                                             0.506                                                                             0.171                                                                              0.668                                                                             1.35                                     prior to amination                                                       13   0.593     54.5 1.197                                                                              0.148                                                                             0.453                                                                             0.164                                                                              0.576                                                                             1.193                                    AMA/L-MnMA/MMA (12.9)                                                                             (28.2)                                                                            (10.5)                                                                            (4.1)                                                                              (13.8)                                                                            (11.3)                                   percent reduction                                                        14   0.593 AMA/L-                                                                            51.2 1.05 0.03                                                                              0.19                                                                              0.09 0.538                                                                             0.819                               MnMA/MMA/MAA                                                                       percent reduction                                                                            (23.7)                                                                             (87.9)                                                                            (62.5)                                                                            (46.8)                                                                             (19.5)                                                                            (39.1)                              __________________________________________________________________________

The actual water volume and total pore volume of some of the adsorbentsin Table II are compared to the respective theoretical water volume andtotal pore volume based on simple pore filling of the porouspost-crosslinked substrate polymer by the surface-modifying monomer orpolymer and are set forth in Table III. The theoretical water volume andpore volume are calculated as shown in equations 1 and 2, respectively.The substrate water and substrate pore volume are expressed as cc pergram of the substrate polymer (cc/g). The surface-modifying polymer isexpressed as grams per grams of substrate polymer (g/g). The density ofthe surface-modifying polymer is that after incorporation into thesubstrate polymer and is estimated using the density of similar polymersprepared by conventional methods. ##EQU1##

Transmission Electron Micrographs (300,000X) of the adsorbentsillustrated in FIGS. 1-6 are obtained from 300 Angstrom thickcross-section of the adsorbents of the invention and indicate that thesurface-modifying polymers are distributed throughout the polymersubstrate.

                                      TABLE III                                   __________________________________________________________________________    Comparison of Theoretical and Actual Water Volumes and Total Pore Volume                        Surface-                                                    Surface-Modifying Polymer                                                     Modifying         Water Volume                                                                        Total Pore Volume                                     Expressed as g/g* of Dry                                                                        Density                                                                             (cc/g)    (cc/g)                                      Example                                                                            Substrate Polymer                                                                          (g/cc)                                                                              Actual                                                                            Theoretical                                                                         Actual                                                                            Theoretical                             __________________________________________________________________________    1    substrate Polymer                                                                          --    1.22                                                                              --    0.73                                                                              --                                      1a   0.022* EGDM  1.10  1.32                                                                              1.18  0.68                                                                              0.70                                    1b   0.044* EGDM  1.10  1.26                                                                              1.13  0.67                                                                              0.66                                    1c   0.089* EGDM  1.10  1.65                                                                              1.05  0.73                                                                              0.60                                    1d   0.178* EGDM  1.10  1.54                                                                              0.90  0.68                                                                              0.48                                    2    substrate polymer                                                                          --    1.30                                                                              --    1.04                                                                              --                                           aminated with dimethylamine                                              2a   0.075* polyamide                                                                           1.10  --  1.15  0.92                                                                              0.90                                    3a   0.75* Nylon  1.14  1.18                                                                              1.15  0.87                                                                              0.91                                    2    substrate polymer                                                                          --    1.43                                                                              --    1.11                                                                              --                                           aminated with dimethylamine                                              4a   0.243* DER ™ 732 Epoxy                                                                  1.06  0.95                                                                              0.97  0.72                                                                              0.70                                    4b   0.243* DER ™ 732/DETA                                                                   1.06  0.95                                                                              0.97  0.54                                                                              0.70                                    2    substrate polymer                                                                          --    1.43                                                                              --    --                                               aminated with dimethylamine                                              5a   0.243* DER ™ 331                                                                        1.16  1.03                                                                              0.98  0.89                                                                              0.72                                    5b   0.243* DER ™ 331/DETA                                                                   1.16  0.92                                                                              0.98  0.75                                                                              0.72                                    2    substrate polymer                                                                          --    1.27                                                                              --    0.98                                                                              --                                           aminated with methylamine                                                6a   0.095* GE Silcone                                                                          1.00  1.09                                                                              1.07  0.88                                                                              0.80                                    __________________________________________________________________________

The data illustrated in Tables II and III are evidence that polymericadsorbent materials that are both incompatible and compatible formolecular level mixing with polystyrene can be produced using thistechnique. Furthermore, this approach can be applied to producematerials with shapes other than spherical beads, such as membranes orfibers by altering the form of the first polymer.

EXAMPLE 19

Nonionic Polymer Immobilized on Post-Crosslinked Macroporous Copolymer

This example illustrates preparation of a surface modification of anadsorbent polymer of the invention, carried out in two stages.

(a) A 1000-mL three-necked round-bottom flask was equipped with anitrogen inlet, a reflux condenser connected to an oil bubbler with anitrogen outlet, and a mechanical air-driven stirrer. The flask wasimmersed into an oil bath and a nitrogen atmosphere was established. Wetporous post-crosslinked polymer of Example 2 prior to amination (100 g),200 mL water, and 8 g of tetrahydrofuran were placed into the flask,followed by 1.80 g methyl methacrylate, 1.80 g allyl methacrylate, and36 mg 2,2'-azo-bis(isobutyronitrile), available under the TradenameVAZO-64® from dupont. The mixture was heated at 85° C. for 3 hours withslow mechanical stirring. The surface-modified adsorbent thus obtainedwas subsequently surface-modified with another polymer as describedbelow.

(b) A mixture of methyl methacrylate (12.5 g), styrene (5.0 g), andvinylbenzylchloride (7.5 g; isomer ratio: 70% metal 30% para) was addedto the mixture of (a) by a syringe pump at 85° C. over 12 hours,constantly maintaining the nitrogen atmosphere. The resulting mixturewas then cooled, the liquid phase removed, and the resultingsurface-modified polymeric adsorbent was washed several times withchloroform. Analysis of the liquid phase and washings on the percentageof solids indicated that the percentage of the surface-modifying polymerimmobilized on the macroporous polymer is over 97 percent.

EXAMPLE 20

Cationic Polymer Immobilized on Post-Crosslinked Macroporous Copolymer

The nonionic surface-modified post-crosslinked adsorbent of Example 19(36.8 g of dry polymer) was placed into a 500-mL three-neckedround-bottom flask equipped with a reflux condenser and a mechanicalair-driven stirrer. Tetrahydrofuran (100 mL) was added to this solution,followed by methyl sulfide (3.0 mL). The resulting mixture was stirredat 35° C. for 16 hours and at 45° C. for an additional one hour. Afterthis, water (100 mL) was added, and unreacted methyl sulfide andtetrahydrofuran were removed by rotary-evaporation.

EXAMPLE 21

Anionic Polymer Immobilized on Post-Crosslinked Macroporous Copolymer

A 1000-mL three-necked round-bottom flask was equipped with a nitrogeninlet, a reflux condenser connected to an oil bubbler with a nitrogenoutlet, and a mechanical stirrer. The flask was immersed into an oilbath and a nitrogen atmosphere was established. The porouspost-crosslinked polymer of Example 2 prior to amination (100 g of wetresin), water (200 mL), and tetrahydrofuran (8 g) were placed into theflask, followed by the methyl methacrylate (1.80 g), allyl methacrylate(1.80 g), and VAZO-64™ (36 mg). This mixture was heated at 85° C. for 3hours with slow mechanical stirring. After this, the mixture of methylmethacrylate (10.0 g), butyl acrylate (7.5 g), and methacrylic acid (7.5g) was added by a syringe pump at 85° C over 12 hours, constantlymaintaining the nitrogen atmosphere. The resulting mixture was cooled,the liquid phase was removed, and the resulting polymeric adsorbent waswashed several times with tetrahydrofuran. Analysis of the liquid phaseand washings on the percentage of solids indicated that the percentageof the surface-modifying polymer immobilized on the post-crosslinkedmacroporous copolymer is about 97 percent.

EXAMPLE 22

This example illustrates separation of compounds by columnchromatography on nonionic surface-modified post-crosslinked adsorbentof Example 19.

A mixture of phenylcyclohexane (30 mg) and ethyl 3-hydroxybenzoate (13mg) was introduced onto a chromatographic column (25.4 cm×1.27 cm)packed with 5.0g of the dry nonionic, surface-modified, post-crosslinkedadsorbent of Example 19 as the stationary phase. The mixture was elutedwith 30 ml of cyclohexane/chloroform (5:1 volume ratio) followed by 100ml of cyclohexane/chloroform (1:1 volume ratio). The eluate from 5:1cyclohexane/chloroform contained 98.7 percent phenylcyclohexane and 1.3percent ethyl 3-hydroxybenzoate. The eluate from 1:1cyclohexane/chloroform contained >99.9 percent ethyl 3-hydroxybenzoate.

EXAMPLE 23

This example illustrates separation of compounds by columnchromatography on cationic surface-modified post-crosslinked adsorbentof Example 20.

A mixture of phenylcyclohexane (30 mg) and 3-phenylbutyric acid (13 mg)was introduced onto a chromatographic column (25.4 cm×1.27 cm) packedwith 5.0 g of the dry nonionic, surface-modified, post-crosslinkedadsorbent of Example 20 as the stationary phase. The mixture was elutedwith 100 ml of cyclohexane followed by 200 ml of cyclohexane/chloroform(1:1 volume ratio). The eluate from the cyclohexane contained >99.9percent phenylcyclohexane. The eluate from 1:1 cyclohexane/chloroformcontained >99.9 percent 3-phenylbutyric acid.

EXAMPLE 24

This example illustrates separation of compounds by columnchromatography on anionic surface-modified post-crosslinked adsorbent ofExample 21.

A mixture of phenylcyclohexane (27 mg) and 2-phenylbutyric acid (27 mg)was introduced onto a chromatographic column (25.4 cm×1.27 cm) packedwith 5.0 g of the dry nonionic, surface-modified, post-crosslinkedadsorbent of Example 21 as the stationary phase. The mixture was elutedwith 50 ml of cyclohexane followed by 150 ml of cyclohexane/chloroform(1:1 volume ratio). The eluate from the cyclohexane contained >99.9percent phenylcyclohexane. The eluate from 1:1 cyclohexane/chloroformcontained >99.9 percent 2-phenylbutyric acid.

What is claimed is:
 1. A polymeric adsorbent material comprising (a) asubstrate of a porous post-crosslinked polymer of at least onemonoethylenically unsaturated monomer and a crosslinking agent, whereinat least one monethylenically unsaturated monomer is styrene and thecrosslinking agent is divinylbenzene, said polymer beingpost-crosslinked by the steps of (i) reacting the polymer with apolyfunctional haloalkylating or acylating agent to form a haloalkylatedor acylated polymer, (ii) swelling the resulting haloalkylated oracylated polymer with an inert swelling agent to form a swollen,haloalkylated or acylated polymer, and then (iii) maintaining theswollen, haloalkylated or acylated polymer at a temperature and in thepresence of a Friedel-Crafts catalyst such that haloalkyl or acylmoieties on the polymer react with an aromatic ring of an adjacentpolymer chain to form a bridging moiety, and (b) at least onenon-optically active, surface-modifying polymer of an ethylenicallyunsaturated monomer, said surface-modifying polymer being incorporatedand immobilized onto the substrate.
 2. The polymeric adsorbent materialof claim 1, wherein the porous post-crosslinked polymer comprises amacroporous polymer comprising from about 1 to about 35 weight percentof divinylbenzene.
 3. The polymeric adsorbent material of claim 1,wherein the porous post-crosslinked polymer comprises a gel polymercomprising from about 0.0 to about 8.0 weight percent of divinylbenzene.4. The polymeric adsorbent of claim 2, wherein the macroporous polymercomprises from about 1 to about 10 percent by weight of divinylbenzene.5. The polymeric adsorbent of claim 1, wherein the surface-modifyingpolymer is derived from a monomer or a polymer which is an acrylate,methacrylate, styrene, functionalized styrene or a combination thereof.